Option C The Blast Furnace This follows closely from IGCSE work If you cant remember the work you did at IGCSE then you need to revise You will learn about some different sources of iron and you will learn more detail about the chemical reactions that happen in a blast furnace ID: 174741
Download Presentation The PPT/PDF document "Chemistry in Industry and Technology" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Chemistry in Industry and Technology
Option CSlide2Slide3
The Blast FurnaceSlide4
This follows closely from IGCSE work. If you can’t remember the work you did at IGCSE then you need to revise!
You will learn about some different sources of iron, and you will learn more detail about the chemical reactions that happen in a blast furnace.Slide5
Syllabus Statements
C1.1 State the main sources of iron.
C1.2 Describe the main reactions that occur in the blast furnace.Slide6
TuyereSlide7
The Iron Ore fed into the blast furnace may be a number of different compounds:
Haematite
Fe
2
O
3
(this is the one you learnt at IGCSE)
Magnetite
Fe3
O
4
Iron Pyrites
FeS
2
(Fool’s gold!)
FeS
2
must be converted to the oxide:
4FeS
2
+ 11O
2
2Fe
2
O
3
+ 8SO
2Slide8
Coke is also fed in at the top.
This provides a source of carbon to reduce the iron oxide.
Fe
2
O
3
+ 3C
2Fe + 3CO
This DOES happen to a small extent – but from IGCSE you know its not really that simple!Slide9
Most of the reduction is done by Carbon Monoxide CO.
C + O
2
CO
2
CO
2
+ C 2COSlide10
This carbon monoxide then reduces the iron ore.
Either
Fe
2
O
3
+ 3CO
2Fe + 3CO
2
Or
Fe
3
O
4
+ 4CO 3Fe + 4CO
2Slide11
Both these reactions are exothermic.
The iron produced is molten because of the high temperature.
(
Iron
melts at 1536 °C or 2797 °F (1811 K). It boils at 2862 °C or 5182 °F (3134 K
).)
It sinks to the bottom of the furnace where it can be “tapped”Slide12
There are 2 more possible reaction mechanisms that you need to learn:
If methane (“natural gas”) is blown into the furnace, then incomplete combustion can take place.
2CH
4
+ O
2
2CO + 4H
2
Then either the CO can act as the reducing agent as before, or the H
2
can act as the reducing agent.
Write balanced equations for hydrogen reducing both the forms of iron oxide present.Slide13
Fe
3
O
4
+ 4H
2
3Fe + 4H
2
O
Fe
2
O
3
+ 3 H
2
2Fe + 3H
2
OSlide14
Getting rid of impurities
The iron ore fed into the blast furnace is NOT a pure chemical.
It contains impurities such as silicon (IV) oxide and aluminium oxide.
These come from the rocks which contain the iron compounds.Slide15
Relative abundance of elements in the Earth’s crust
Oxygen
46.6%
Silicon
27.7%
Aluminum
8.1%
Iron
5.0%
Calcium
3.6%
Potassium
2.6%
Magnesium
2.6% Slide16
The third raw material added at the top of the blast furnace is powdered limestone.
This decomposes at the high temperatures involved.
CaCO
3
CaO
+ CO
2
Calcium oxide is “quicklime”
Quicklime is very basic and reacts with the impurities we have mentioned.Slide17
CaO
+ SiO
2
CaSiO
3
CaO
+ Al
2
O
3
CaAl
2
O
4
Silicon oxide is a non-metal oxide and is therefore acidic.
Aluminium oxide is amphoteric!!Slide18
Both the compounds formed are liquids.
We call them “slag”
They float on top of the molten iron and can be removed through a second outlet.
They are used for roads and making cement.
Because they can be easily removed the blast furnace can be run continuously for a number of years
(good economics!).
Eventually the lining of the furnace breaks down and we have to let the whole thing cool down so we can replace it.Slide19
Reminder . . .
C1.1 State the main sources of iron.
C1.2 Describe the main reactions that occur in the blast furnace.Slide20
Summary . . .Slide21
TuyereSlide22